In enzymology, a glycosaminoglycan galactosyltransferase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are UDP-galactose and glycosaminoglycan, whereas its two products are UDP and D-galactosylglycosaminoglycan.
This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is UDP-galactose:glycosaminoglycan D-galactosyltransferase. This enzyme is also called uridine diphosphogalactose-mucopolysaccharide galactosyltransferase.